LANCASTER, Pa. — On that cold first day of winter, in the early morning, two girls armed with a knife, a rope and six months of accelerating jealousy took the joy of Hazel Show's motherhood away.

They slashed the throat of 16-year-old Laurie Show simply because one of them thought Laurie had tried to steal her boyfriend.

Laurie's bedroom remains as it was on Dec. 20, 1991, filled with her favorite stuffed bears and treasured photos. Gone are the bloodstains and telltale footprints.

On dismal days, and there are many, Hazel Show finds her greatest solace in this room, though it is the place she experienced her greatest pain. Sometimes, somehow, sitting here can make Laurie seem alive, as evidenced by how often Show slips and refers to her daughter in the present tense.

From one mother's fierce grief has come a sense of purpose she'd never known before. Show is determined, she says, to prevent her daughter's fate from becoming anyone else's.

With Show's efforts at the fore, Pennsylvania became the latest state to pass stronger legislation outlawing stalking--laws that might have saved her only child from an obsessive teen-ager named Lisa Michelle Lambert.

Show petitioned legislators for nearly a year and organized a statewide petition drive to get the stalking law on the books. It was signed into law in late June.

"Laurie was my life," Show says simply. "I had to do something."

*

Laurie Show was buried in her prized Penn State sweat shirt two days before Christmas, her hands clasping pictures of the classmates who lined up 600 strong in a frozen rain to say goodby.

Eighteen months later, four families remain splintered.

Two young women, Michelle Lambert and Tabitha Faith Buck, are in prison for life. Michelle's former boyfriend, Lawrence Yunkin, whose brief affections for Laurie were at the root of it all, is serving 10 to 20 years after pleading guilty to third-degree murder in exchange for leniency--which was revoked when prosecutors contended he lied at Michelle and Tabitha's trial.

At the time of the murder, Yunkin was 20, Michelle 18 and Tabitha 17.

Laurie was a sophomore at Conestoga Valley High School in East Lampeter Township, a suburb that separates Lancaster from the Amish country for which it is so well known.

In July, 1991, she spent a week hanging out with Yunkin, a high-school dropout who worked at a nearby lumberyard.

As Show recounts it, Laurie didn't view it as dating. She testified that Yunkin raped her daughter, and learned Michelle was pregnant shortly after. Whatever relationship Laurie and Yunkin had ended after that week.

But Michelle Lambert didn't believe it.

Over the following months, she became convinced Laurie was trying to steal her boyfriend. She called the Shows' condo to scream at Laurie and ignored Hazel Show's demands to stop.

It became a pattern. Michelle, often accompanied by Yunkin and friends, would confront Laurie at the Deb Shop, the clothing store where Laurie worked. She would show up at other public places to pelt Laurie and her mother with obscenities and warn the teen to stay away from Yunkin.

The Shows filed simple assault charges after Michelle pushed Laurie to the ground, and an East Lampeter Township investigator began working on the case--four days before Laurie died.

The Show case shook up this town; it was something residents could not get out of their minds.

"I think it was the fact that they were all middle-class youths with no mental illnesses," said Jack A. Kenneff, the Lancaster County first assistant district attorney who prosecuted all three defendants. "People just couldn't accept that this kind of thing could happen to that kind of people."

*

To get Laurie alone in the Shows' condo the morning of Dec. 20, the girls created a diversion.

The afternoon before, Hazel Show received a call at work from a "Mrs. Cooper," the name of a school counselor, who said Laurie had gotten into some trouble with a boy.

Her daughter protested that she hadn't done anything wrong, but Show decided to go to the school anyway, just to clear things up.

When she left the next morning, Laurie was drying her hair, wearing her sweats, preparing for the final day of school before Christmas break.

Show drove to the school, but found no one. After waiting several minutes, she returned home and was met by a neighbor, who mentioned hearing loud noises. Then she saw the open door.

She ran upstairs and found Laurie on the floor, her arms moving.

"She breathed deeply and I went to pick her up to cradle her. That's when I saw her throat was cut," Show said. "I said, 'Honey, I'm so sorry--it was a setup. Who did this to you?'

"She said, 'Michelle did it. Michelle. Michelle.' And then she said, 'Love you, love you, love you' four times. I told her God was going to take care of her. And I just held her."